Mite allergoids coupled to nonoxidized mannan from Saccharomyces cerevisae efficiently target canine dendritic cells for novel allergy immunotherapy in veterinary medicine

Abstract

We have recently reported that grass pollen allergoids conjugated with nonoxidized mannan of Saccharomyces cerevisae using glutaraldehyde results in a novel hypoallergenic mannan-allergen complex with improved properties for allergen vaccination. Using this approach, human dendritic cells show a better allergen uptake and cytokine profile production (higher IL-10/IL-4 ratio) for therapeutic purposes. Here we aim to address whether a similar approach can be extended to dogs using canine dendritic cells. Six healthy Spanish Greyhound dogs were used as blood donors to obtain canine dendritic cells (DC) derived from peripheral blood monocytes. Allergens from Dermatophagoides farinae mite were polymerized and conjugated with nonoxidized mannan. Nuclear magnetic resonance (NMR), gel electrophoresis (SDS-PAGE), immunoblotting and IgE-ELISA inhibition studies were conducted to evaluate the main characteristics of the allergoid obtained. Mannan-allergen conjugate and controls were assayed in vitro for canine DC uptake and production of IL-4 and IL-10. The results indicate that the conjugation of D. farinae allergens with nonoxidized mannan was feasible using glutaraldehyde. The resulting product was a polymerized structure showing a high molecular weight as detected by NMR and SDS-PAGE analysis. The mannan-allergen conjugate was hypoallergenic with a reduced reactivity with specific dog IgE. An increase in both allergen uptake and IL-10/IL-4 ratio was obtained when canine DCs were incubated with the mannan-allergen conjugate, as compared with the control allergen preparations (unmodified D. farinae allergens and oxidized mannan-allergen conjugate). We conclude that hypoallergenic D. farinae allergens coupled to nonoxidized mannan is a novel allergen preparation suitable for canine allergy immunotherapy targeting dendritic cells.

Oral myeloid cells uptake allergoids coupled to mannan driving Th1/Treg responses upon sublingual delivery in mice

“…We previously demonstrated that PM‐allergoids are much better captured than native allergens by human16 and canine17 DCs and that this property is lost upon mannan oxidation. Here we show that this is also the case in mice when assessing antigen‐presenting cells (CD45 + MHC‐II + ) from the sublingual mucosa.…”

“…In the case of PM‐allergoids, however, their low IgE binding reactivity16, 17, 18 would make this mechanism unlikely. Nevertheless, other IgE‐independent mechanisms for allergen uptake have been described further, like CD207 (Langerin), a putative mannose receptor,32, 33 or CD209 (DC‐SIGN) 34.…”

“…A relevant point of the present study is that the cells used for allergen uptake were resident cells obtained directly from the oral mucosa in a steady‐state situation. Thus, it appears that PM‐allergoids are better uptaken by either resident DCs or monocyte‐derived DCs 16, 17…”

“…We previously reported that polymerized allergoids coupled to nonoxidized mannan derived from Saccharomyces cerevisae (PM‐allergoids) are better captured than native allergens by human16 and canine17 DCs. PM‐allergoids are taken up by DCs very rapidly through a receptor‐mediated mechanism involving C‐type lectin receptors 16.…”

“…PM‐allergoids are taken up by DCs very rapidly through a receptor‐mediated mechanism involving C‐type lectin receptors 16. Besides their better uptake, these glycoconjugates are rendered hypoallergenic16, 17, 18 and able to activate DCs to promote the induction of functional FOXP3 + Treg cells,16 thus with improved features for allergen immunotherapy 19. These properties may be especially relevant for SLIT due to the very short time the allergens are available to mucosal DCs, which might well explain the high allergen doses needed for clinical efficacy in SLIT 12, 14.…”